Proteolytic activity and cleavage specificity of cathepsin E at the physiological pH as examined towards the B chain of oxidized insulin

• Published in: FEBS letters 1991-11, Vol.292 (1), p.53-56
• Main Authors: Athauda, Senarath B.P., Takahashi, Takayuki, Inoue, Hideshi, Ichinose, Masao, Takahashi, Kenji
• Format: Article
• Language: English
• Subjects: activity; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; B chain of oxidized insulin; Biological and medical sciences; Cathepsin E; Cathepsins - metabolism; Chromatography, High Pressure Liquid; Cleavage specificity; cya; cysteic acid; effects on; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Gastric Mucosa - enzymology; Gastric mucosal aspartic proteinase; Humans; Hydrogen-Ion Concentration; Hydrolases; Hydrolysis; insulin; Insulin - metabolism; Molecular Sequence Data; nitrophenylalanine; Nph; Oxidation-Reduction; PAGE; polyacrylamide gel electrophoresis; Proteolytic activity; SDS; sodium dodecyl sulfate; specificity; Substrate Specificity
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(91)80832-N

Proteolytic activity and cleavage specificity of cathepsin E were investigated in a wide range of pHs from 3.0 to 10.5 using the B chain of oxidized insulin as substrate. Contrary to the previous notion that cathepsin E is virtually inactive above pH 6, significant proteolytic activity was observed at pH 7.4 and above. Further, cleavage specificity appeared to change significantly with pH and rather specific cleavage occurred at pH 7.4 and above as compared to pH 5.5 and 3.0. These results suggest that cathepsin E may function in vivo at the physiological pH with a rather restricted specificity.